The present invention is a hydrosilation process where a silicon hydride is reacted with an unsaturated reactant in the presence of a platinum catalyst and an aldehyde accelerator. The aldehyde accelerators are especially useful for facilitating the hydrosilation of unsaturated reactants where the unsaturation is in the internal portion of the reactant's structure, for example, as in cyclopentene and cyclohexene.
It is known in the art to produce organosilicon compounds by reacting a silicon hydride containing compound with an unsaturated organic compound in the presence of a catalyst. This reaction is typically referred to as hydrosilation or hydrosilylation. Typically the catalyst is platinum metal on a support, a platinum compound usually in a solvent, or a platinum complex.
In Speier et al., U.S. Pat. No. 2,823,218, a method for the production of organosilicon compounds by reacting an Si--H with a compound containing aliphatic carbon atoms linked by multiple bonds in the presence of chloroplatinic acid is taught. Lamoreaux, U.S. Pat. No. 3,220,972, teaches a similar process, however the catalyst is a reaction product of chloroplatinic acid. Lamoreux, supra, teaches the catalyst may be a complex of PtCl.sub.2 and an ether and aldehyde derived from octyl alcohol.
One of the major problems known in the art with hydrosilation reactions is the de-activation of the catalyst prior to the completion of the reaction. One method for reactivation of the catalyst has been to expose the reaction mixture to oxygen. For example, Onopchenko et al., U. S. Pat. No. 4,578,497, teach the use of an oxygenated platinum containing catalyst for use in hydrosilating alkylsilanes. Kleyer et al., U.S. Pat. No. 5,359,111, disclose a method for controlling hydrosilation reaction mixtures by controlling the solution concentration of oxygen in the reaction mixture, relative to the platinum present in the reaction mixture.
In addition to the problem of de-activation of the platinum catalyst, hydrosilation processes taught in the art are not particularly effective in hydrosilating internal unsaturated bonds in organic molecules. The present inventors have unexpectedly discovered that certain aldehydes can act as accelerators for platinum catalyzed hydrosilation processes. The aldehyde accelerators are particularly effective in facilitating the hydrosilation of internal unsaturated bonds of organic molecules.
Bank et al., U.S. Pat. No. 5,424,470, teach a hydrosilation process where silicon hydride is reacted with an unsaturated reactant in the presence of platinum catalyst and an unsaturated ketone accelerator.
Bank et al., U.S. Pat. No. 5,449,802, teach a hydrosilation process where silicon hydride is reacted with an unsaturated reactant in the presence of platinum catalyst and an accelerator selected from a group consisting of acetylenic alcohols, silated acetylenic alcohols, and acetylenic ethers.